Problem: Vanessa had to do problems 48 through 87 for homework last week. If Vanessa did all of the problems she was assigned, how many problems did she do?
Instead of counting problems 48 through 87, we can subtract 47 from each number so we instead consider problems 1 through 40. We see that Vanessa did 40 problems. Notice that she did 40 and not 39 problems.